1. Field of the Invention
The present invention relates to a structure of a multichip resin-encapsulated semiconductor device and a method of manufacturing the same.
2. Description of the Related Art
Along with the needs of reduction in size and weight and improvement in function of electronic equipment, high density mounting of semiconductor parts into the electronic equipment is demanded, and in recent years, there have been required smaller and thinner semiconductor devices suitable for high integration.
In the context of such a trend, various types of semiconductor devices are proposed in response to various applications, such as a gull-wing type, a leadless type, a BGA type, and a wafer level package. Further, under recent environment in which reduction in product price is desired, those semiconductor devices are required to be provided in a cheaper price, as well as the small size and the highly integrated function. For example, in order to obtain the more highly integrated function, in a related-art semiconductor device, as illustrated in FIG. 7A, the following configuration is provided. That is, the semiconductor device includes: a semiconductor element 1; an adhesive for mounting the semiconductor element 1 on a die pad 23 which is provided on a substrate 10; metal wires 9 for connecting a plurality of wiring lines 20 provided on the substrate 10 to each other; and an encapsulation resin 11 for encapsulating the semiconductor element 1, the adhesive, the metal wires 9, and the plurality of wiring lines 20. On another surface of the substrate 10, solder balls 22 are formed as external terminals on respective external connection portions 21, that is, the semiconductor device has a structure called a ball grid array (BGA).
For the substrate 10, a heat-resistant substrate typified by a bismaleimide resin (BT resin) is used. The die pad 23 mounting the semiconductor element 1 and the plurality of wiring lines 20 are formed on one surface of the substrate, and the external connection portion 21 is formed on the another surface of the substrate. Via through holes 24 formed in the substrate 10, each of which is covered with a conduction layer, the respective surfaces are connected to each other. The solder balls 22, which electrically and physically connect a semiconductor encapsulation member and a mounting substrate to each other, are mounted on the external connection portion 21 in a lattice or zigzag arrangement (see, for example, Japanese Patent Application Laid-open No. 07-193162).
However, in the related-art BGA resin-encapsulated semiconductor device, unlike a semiconductor package using a metal lead frame, there is used a double-sided substrate or a multilayer wiring substrate, which uses a heat-resistant resin as a base, and hence steps of forming the substrate become complicated. For example, when the substrate is manufactured, it is necessary to manufacture a mask for circuit formation, for forming the wiring on the mounting surface side on which the semiconductor device is mounted, and for forming the external connection terminal on the another side. In addition, during the formation of the substrate, it is necessary to carry out resist coating, exposure and development, resist patterning, forming of the through hole and plating for electrically connecting the wiring and the external connection terminal to each other, resist separation processing, and adhesion of the substrates. As a result, there has been a problem in that the unit price per one substrate becomes more expensive than that in a case where the metal lead frame is used, and the total package cost becomes high.
Further, as illustrated in FIGS. 7B and 7C, when multichip packaging or module packaging is performed in which a plurality of semiconductor elements and electronic components are mounted on one semiconductor device, there are adopted modes in which a plurality of semiconductor elements are mounted side by side or are vertically stacked on a substrate. Thus, as the number of semiconductor elements or electronic components to be mounted increases, the size of the semiconductor device increases, which makes it difficult to provide smaller and thinner highly integrated electronic equipment using the semiconductor device.